<?php
/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2011 PHPExcel
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category   PHPExcel
 * @package    PHPExcel_CachedObjectStorage
 * @copyright  Copyright (c) 2006 - 2011 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
 * @version    1.7.6, 2011-02-27
 */


/**
 * PHPExcel_CachedObjectStorage_DiscISAM
 *
 * @category   PHPExcel
 * @package    PHPExcel_CachedObjectStorage
 * @copyright  Copyright (c) 2006 - 2011 PHPExcel (http://www.codeplex.com/PHPExcel)
 */
class PHPExcel_CachedObjectStorage_DiscISAM extends PHPExcel_CachedObjectStorage_CacheBase implements PHPExcel_CachedObjectStorage_ICache {

    private $_fileName = null;
    private $_fileHandle = null;


    private function _storeData() {
        $this->_currentObject->detach();

        fseek($this->_fileHandle,0,SEEK_END);
        $offset = ftell($this->_fileHandle);
        fwrite($this->_fileHandle, serialize($this->_currentObject));
        $this->_cellCache[$this->_currentObjectID]    = array('ptr' => $offset,
                                                            'sz'  => ftell($this->_fileHandle) - $offset
                                                           );
        $this->_currentObjectID = $this->_currentObject = null;
    }    //    function _storeData()


    /**
     *    Add or Update a cell in cache identified by coordinate address
     *
     *    @param    string            $pCoord        Coordinate address of the cell to update
     *    @param    PHPExcel_Cell    $cell        Cell to update
     *    @return    void
     *    @throws    Exception
     */
    public function addCacheData($pCoord, PHPExcel_Cell $cell) {
        if (($pCoord !== $this->_currentObjectID) && ($this->_currentObjectID !== null)) {
            $this->_storeData();
        }

        $this->_currentObjectID = $pCoord;
        $this->_currentObject = $cell;

        return $cell;
    }    //    function addCacheData()


    /**
     * Get cell at a specific coordinate
     *
     * @param     string             $pCoord        Coordinate of the cell
     * @throws     Exception
     * @return     PHPExcel_Cell     Cell that was found, or null if not found
     */
    public function getCacheData($pCoord) {
        if ($pCoord === $this->_currentObjectID) {
            return $this->_currentObject;
        }
        $this->_storeData();

        //    Check if the entry that has been requested actually exists
        if (!isset($this->_cellCache[$pCoord])) {
            //    Return null if requested entry doesn't exist in cache
            return null;
        }

        //    Set current entry to the requested entry
        $this->_currentObjectID = $pCoord;
        fseek($this->_fileHandle,$this->_cellCache[$pCoord]['ptr']);
        $this->_currentObject = unserialize(fread($this->_fileHandle,$this->_cellCache[$pCoord]['sz']));
        //    Re-attach the parent worksheet
        $this->_currentObject->attach($this->_parent);

        //    Return requested entry
        return $this->_currentObject;
    }    //    function getCacheData()


    /**
     *    Clone the cell collection
     *
     *    @return    void
     */
    public function copyCellCollection(PHPExcel_Worksheet $parent) {
        parent::copyCellCollection($parent);
        //    Get a new id for the new file name
        $baseUnique = $this->_getUniqueID();
        $newFileName = PHPExcel_Shared_File::sys_get_temp_dir().'/PHPExcel.'.$baseUnique.'.cache';
        //    Copy the existing cell cache file
        copy ($this->_fileName,$newFileName);
        $this->_fileName = $newFileName;
        //    Open the copied cell cache file
        $this->_fileHandle = fopen($this->_fileName,'a+');
    }    //    function copyCellCollection()


    public function unsetWorksheetCells() {
        if(!is_null($this->_currentObject)) {
            $this->_currentObject->detach();
            $this->_currentObject = $this->_currentObjectID = null;
        }
        $this->_cellCache = array();

        //    detach ourself from the worksheet, so that it can then delete this object successfully
        $this->_parent = null;

        //    Close down the temporary cache file
        $this->__destruct();
    }    //    function unsetWorksheetCells()


    public function __construct(PHPExcel_Worksheet $parent) {
        parent::__construct($parent);
        if (is_null($this->_fileHandle)) {
            $baseUnique = $this->_getUniqueID();
            $this->_fileName = PHPExcel_Shared_File::sys_get_temp_dir().'/PHPExcel.'.$baseUnique.'.cache';
            $this->_fileHandle = fopen($this->_fileName,'a+');
        }
    }    //    function __construct()


    public function __destruct() {
        if (!is_null($this->_fileHandle)) {
            fclose($this->_fileHandle);
            unlink($this->_fileName);
        }
        $this->_fileHandle = null;
    }    //    function __destruct()

}
